/Dev/sr0 and/dev/CDROM

 

And/dev/CDROM

Luo Weifeng 2011-5-17

Reprinted Reserved: http://blog.csdn.net/luoweifeng1989/archive/2011/05/17/6426193.aspx

 

 

This problem seems to have plagued me for a short time, because I want to view the CD mount point. After using the mount command to view the mount point, the device/dev/sr0 is mounted to the disk I prepared, I tried umount to mount this device, and there was no difference after I mounted it with/dev/CDROM. Then I checked the device node and found the following:

It turns out that/dev/CDROM is just a symbolic link to sr0. So what exactly does Sr mean? Google found that there was a buddy in the mail list who was depressed. The excerpt is as follows:

> <Br/> on Wed, Nov 4, 2009 at pm, Derek Broughton <br/> <derek@pointerstop.ca> wrote: <br/> Verde denim wrote: <br/> on Tue, Nov 3, 2009 at AM, derek Broughton <br/> <derek@pointerstop.ca> wrote: <br/> translation-I don't know either... LOL <br/> actually, I 'd already said that-and suggested "Raw" as a <br/> wild guess. but <br/> I was intrigued that Detlef thought that knowing what it stood <br/> for wocould <br/> prevent errors, since I really can't imagine how most of us <br/> wocould need to <br/> know it. <br/> -- <br/> Derek <br/> and knowing the acronym definitions probably won't help the learning <br/> too much, either. <br/> but, according to the Linux SCSI sub-system documentation I have, it <br/> wocould have to stand for _ SCSI _ read _ since it is a CD drive that is <br/> designated read-only. for generic operations on the same device, it <br/> wocould map to sg0 (_ SCSI _ generic _) in order to gain the write perm. <br/> apparently all of the devices like/dev/sr0,/dev/st0,/dev/nst0x Map <br/> to an SG device for generic operations. <br/> although _ raw _ seems to be a good logical choice. <br/> Lo has C had it right. <br/> but you shoshould read the code from orbit. it's the only way to make sure. <br/> from a 2.4 kernel source <br/> Drivers/SCSI/SD. c <br/> static struct scsi_device_template sd_template ={< br/> name: "disk", <br/> tag: "SD", <br/> scsi_type: type_disk, <= "D" for disk <br/> Major: scsi_disk0_major, <br/>/* <br/> * Secondary range of majors that this driver handles. <br/> */<br/> min_major: scsi_disk1_major, <br/> max_major: scsi_disk7_major, <br/> BLK: 1, <br/> detect: sd_detect, <br/> init: sd_init, <br/> finish: sd_finish, <br/> attach: sd_attach, <br/> detach: sd_detach, <br/> init_command: sd_init_command, <br/>}; <br/> Drivers/SCSI/St. c <br/> static struct scsi_device_template st_template = <br/> {<br/> name: "tape", <br/> tag: "St ", <br/> scsi_type: type_tape, <= "T" for tape <br/> Major: scsi_tape_major, <br/> detect: st_detect, <br/> init: st_init, <br/> attach: st_attach, <br/> detach: st_detach <br/>}; <br/> Drivers/SCSI/SR. c <br/> static struct scsi_device_template sr_template = <br/> {<br/> name: "CDROM", <br/> tag: "Sr ", <br/> scsi_type: type_rom, <= "R" for Rom <br/> Major: scsi_cdrom_major, <br/> BLK: 1, <br/> detect: sr_detect, <br/> init: sr_init, <br/> finish: sr_finish, <br/> attach: sr_attach, <br/> detach: sr_detach, <br/> init_command: sr_init_command <br/>}; <br/> from a 2.6 kernel source <br/> Drivers/SCSI/SR. c <br/> module_description ("scsi cdrom (SR) driver"); <br/> module_license ("GPL"); <br/> module_alias_blockdev_major (scsi_cdrom_major ); <br/> module_alias_scsi_device (type_rom); <br/> module_alias_scsi_device (type_worm ); <br/> -- <br/> sktsee <br/> -- <br/> Ubuntu-Users Mailing List <br/> ubuntu-users@lists.ubuntu.com <br/> modify settings or unsubscribe: https://lists.ubuntu.com/mailman/listinfo/ubuntu-users <br/> 

We can see that:

Sr stands for SCSI + Rom

SD represents SCSI + Disk

SG represents SCSI + generic

St represents SCSI + tape